Fix for kernel 4.11+

Signal related functions (flush_signal, allow_signal and
signal_pending) moved from include/linux/sched.h to
include/linux/sched/signal.h in 4.11.0:

http://elixir.free-electrons.com/linux/v4.10.17/source/include/linux/sched/signal.h

As a result, this module did not build in 4.11 on my Arch system.

This updates the includes to allow this module to build on 4.11.

include/osdep_service_linux.h

@@ -46,6 +46,9 @@
 #endif
 	#include <linux/sem.h>
 	#include <linux/sched.h>
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0))
+	#include <linux/sched/signal.h>
+#endif
 	#include <linux/etherdevice.h>
 	#include <linux/wireless.h>
 	#include <net/iw_handler.h>